This invention relates to machines for forming plastic bags. In such machines opposed heat seal bars that contain electrically heated elements are pressed together to form a weld, as for the bottom of a bag, and a slitter knife is moved by an endless belt across the width of the web to sever one finished bag from the next in line.
Machines of this type have been successful within a range of widths of web and speeds of operation. It is desired, however, to employ the same type of operation across much wider web paths, for instance for acting upon multiple webs at once, to operate the machines at faster speeds, to provide long-life components, and to provide more accurate operation. To achieve these capabilities it is impossible simply to scale up smaller or slower machines, because the tendency for distortion of the mechanical components has an increasing detrimental effect.
The purpose of the present invention is to provide design features which overcome these difficulties and permit the construction of a wide bag making machine, as wide as 90 inches, that is capable of very high speeds of operation.